<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>
    <button>按钮5</button>
    <script>
        //获得所有按钮元素
        var btns = document.getElementsByTagName('button');
        //为所有按钮元素注册相同事件处理函数
        for(var i = 0; i<btns.length ;i++){
            btns[i].onclick = changeColor;
        }
        function changeColor(){
            for (var j=0; j<btns.length; j++){
                if (btn[j] === this){
                    //设置当前按钮的背景颜色
                    this.style.backgroundColor = 'pink';
                }else{
                    //去掉其他按钮的背景颜色
                    btns[j].style.backgroundColor = '';
                }
            }
        }
    </script>
</body>
</html>